The present invention relates to an improvement in a system for recording a digital video datastream and, more particularly, to a system capable of efficiently recording an MPEG transport stream to be digitally broadcasted. The present invention further relates to a system for recording support information of an MPEG transport stream in a management area.
In recent years, TV broadcast has entered an era of digital broadcast and, hence, the necessity of a streamer (an apparatus for saving digital data intact) for digital TV broadcast has come forth.
Digital TV broadcast currently uses an MPEG transport stream, which will probably become a standard in the field of digital broadcast of moving pictures in the near future.
As a streamer for recording digital broadcast data, for example, D-VHS (digital VHS) is available.
Digital TV broadcast data is broadcasted from a broadcast station via a communication satellite. The broadcasted digital data is received by a Set Top Box (to be abbreviated as an STB hereinafter as needed) set in each home, and is displayed on a TV monitor. This STB decrypts and plays back encrypted digital data on the basis of a key code distributed from the broadcast station.
Data is encrypted to prevent a user who does not have any contract with the broadcast station from illicitly receiving and viewing that data.
When the received data is directly played back, it is decrypted by the STB. The decrypted data is decoded by an MPEG decoder, and the decoded data is converted into a TV signal by a video encoder to be displayed on a TV monitor.
When broadcast data is recorded, digital data received by a tuner is recorded by a D-VHS recorder via an IEEE1394 digital interface.
Note that IEEE1394 specifies standard interface specifications, that implement command and data exchanges.
When recorded broadcast data is played back, the recorded data is read from the D-VHS recorder, and is sent to a data expansion unit in the STB, thus playing back the recorded data.
Digital data recorded by the D-VHS recorder normally has the following structure.
That is, digital data to be recorded is recorded as main data in a sync block in a main data area, while six tracks are handled as one ECC block. In this case, a header is appended to a transport stream (TS) packet upon recording.
In such D-VHS streamer, the broadcasted bitstream is directly recorded on tape. For this reason, a plurality of multiplexed programs are recorded on the tape.
Hence, all data are output from the tape upon playback irrespective of the playback start position. The STB selects only a desired program from the output data and plays it back.
Such system suffers very poor random-access performance, since a tape medium is used to record. For this reason, even when the user wants to quickly reach a desired position of a given program to play it back, such random access is impossible to attain.
On the other hand, even in large-capacity disc media such as DVD-RAMS and the like, recording of a streamer suffers certain problems. To realize random access, special playback, and the like, such DVD system inevitably requires to record management data together with broadcast data.
Also, in such DVD system, data must be managed or formatted in accordance with the DVD video format.
However, since the DVD video format does not assume satellite broadcast, it cannot often support special playback or the like.
Japanese Patent Application No. JP10-040876 has proposed the format that assumes a home recorder/player. However, even in this format, digital broadcast is not taken into consideration.
As mentioned above, in a digital TV broadcast compatible streamer system, TS stream data cannot be efficiently managed in a streamer that uses a DVD-RAM capable of random access, i.e., a read/write (R/W) disc.